Miniature pump for liquid cooling system

ABSTRACT

A miniature pump in accordance with the present invention comprises a pump casing ( 1 ) and a liquid circulating unit ( 2 ) received in the pump casing. The pump casing defines an enclosed space ( 15 ) for storing liquid therein. A spacing plate ( 12 ) is arranged in the pump casing to divide the enclosed space into a first chamber ( 16 ) and a second chamber. The spacing plate defines a through opening ( 122 ) at a center portion thereof to make the first and second chambers communicate with each other. An inlet ( 104 ) and an outlet ( 110 ) are formed on the pump casing respectively communicating with the first and second chambers. The liquid circulating unit is mounted in the second chamber for circulating the liquid in a liquid cooling system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to a co-pending U.S. patent application entitled “MINIATURE PUMP FOR LIQUID COOLING SYSTEM”, filed Dec. 17, 2004, and assigned Ser. No. 11/015,488, with the same assignee as the instant application. The disclosure of the above-identified application is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to pumps, and more particularly to a miniature pump for a liquid cooling system for cooling an electronic package.

BACKGROUND

With continuing development of the computer technology, electronic packages such as the CPUs are generating more and more heat that is required to be dissipated immediately. The conventional heat dissipating devices such as combined heat sinks and fans are not competent for dissipating so much heat any more. Liquid cooling systems have thus been increasingly used in computer technology to cool these electronic packages.

A typical liquid cooling system comprises a heat absorbing unit for absorbing heat from a heat source, and a heat dissipating unit which is filled with liquid. The liquid conducts heat exchange with the heat absorbing unit, thereby taking away the heat of the heat absorbing unit as the liquid is circulated. Typically, a miniature pump is used to circulate the liquid.

The pump comprises an inlet for inputting liquid and an outlet for outputting liquid. The inlet and the outlet are in communication with an inner space of the pump where an impeller having blades is installed. The liquid is circulated in the liquid cooling system by spinning of the impeller. A problem existing in the conventional liquid cooling system is that in operation the liquid entering the inner space via the inlet directly strikes the blades, which causes a flow turbulence in the inner space of the pump. This flow turbulence slows down the circulation of the liquid and therefore lowers the cooling efficiency of the whole system.

For the foregoing reasons, there is a need for eliminating such a flow turbulence in the pump.

SUMMARY OF THE INVENTION

The present invention is directed to a miniature pump which can eliminate the flow turbulence therein.

A miniature pump in accordance with the present invention comprises a pump casing and a liquid circulating unit received in the pump casing. The pump casing defines an enclosed space for storing liquid therein. A spacing plate is arranged in the pump casing to divide the enclosed space into a first chamber and a second chamber. The spacing plate defines a through opening at a center portion thereof to make the first and second chambers intercommunicate. An inlet and an outlet are formed on the pump casing respectively communicating with the first and second chambers. The liquid circulating unit is mounted in the second chamber for circulating the liquid in a liquid cooling system.

Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of the preferred embodiments of the present invention with attached drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, isometric view of a miniature pump according to a preferred embodiment of the present invention;

FIG. 2 is an assembled view of the miniature pump of FIG. 1;

FIG. 3 is a cross sectional view of the miniature pump of FIG. 2, but viewed from another aspect; and

FIG. 4 is a cross sectional view of a miniature pump according to an alternative embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1 and 2, a miniature pump in accordance with a preferred embodiment of the present invention comprises a pump casing 1 having an inner space, and a liquid circulating unit 2 and a motor driving unit 3 received in the inner space of the pump casing 1.

The pump casing 1 comprises a hollow main body 11, a top cover 10 hermetically attached to a top end 101 of the main body 11, and a bottom cover 19 attached to a bottom end 102 of the main body 11. A sealing ring 108 is disposed between the main body 11 and the top cover 10 to prevent liquid leakage. The top cover 10 forms an annular groove 106 at a bottom edge thereof for receiving a sealing ring 108 therein. An inlet 104 is formed on the top cover 10 for allowing liquid to enter the pump casing 1. An outlet 110 is formed on the main body 11 for allowing the liquid to exit the pump casing 1.

The main body 11 transversely forms an inner partition wall 14. This partition wall 14 effectively divides the inner space of the main body 11 into a top space 15 and a bottom space 18.

Referring also to FIG. 3, a spacing plate 12 is transversely arranged in the main body 11 as a guide means. The spacing plate 12 further divides the top space 15 of the main body 11 into a first chamber 16 between the spacing plate 12 and the top cover 10, and a second chamber 17 between the partition wall 14 and the spacing plate 12. A positioning hole 120 is defined in the spacing plate 12 at a center thereof. A plurality of through openings 122 is defined in the spacing plate 12 adjacent the positioning hole 120 to make the first and second chambers 16, 17 intercommunicate.

The liquid circulating unit 2 is mounted in the second chamber 17 of the pump casing 1. The liquid circulating unit 2 comprises a shaft 20 mounted between the partition wall 14 and the spacing plate 12, a bearing 22 pivotably attached to the shaft 20 and an impeller 26 attached to the bearing 22. Alternatively, the bearing 22 may be integrated with the impeller 26. The impeller 26 comprises a plurality of blades extending from a center portion to an outer edge portion of the impeller 26. A first permanent magnet 260 is embedded in the impeller 26. The first permanent magnet 260 has a ring flat body magnetized as having a plurality of alternating N and S poles along the ring body. For positioning the shaft 20, the partition wall 14 forms a shaft support 140 having a blind hole (not labeled) receiving a bottom end of the shaft 20 therein, and a top end of the shaft 20 engages in the positioning hole 120 of the spacing plate 12. A pair of locking rings 24 is attached to the shaft 20 near opposite ends thereof respectively for limiting axial movement of the shaft 20.

The motor driving unit 3 is received in the bottom space of the pump casing 1. The motor driving unit 3 is positioned on the bottom cover 19 and comprises a motor having a rotor 34 and a printed circuit board 31 for controlling spinning of the rotor 34. A second permanent magnet 340 is attached to the rotor 34 for spinning therewith, corresponding to the first permanent magnet 260 with a flux gap formed therebetween. Like the first permanent magnet 260, the second permanent magnet 340 also has a ring flat body magnetized as having a plurality of alternating N and S poles along the ring body. An axial flux gap is cooperatively created between the first and second permanent magnets 260, 340. The rotor 34 is covered with a layer of magnetically conductive material; therefore the second permanent magnet 340 is attached to the rotor 34 by magnetic attractive force. Alternative means such as adhesive may be used to attach the second permanent magnet 340 to the rotor 34.

In operation, the rotor 34 of the motor of the motor driving unit 3 rotates to drive the second permanent magnet 340 to rotate therewith. The first permanent magnet 260 is driven to rotate with second permanent magnet 340 by the attractive force therebetween. The impeller 26 thus rotates with the first permanent magnet 260 to circulate the liquid in the liquid cooling system.

In the present invention, the liquid enters the first chamber 16 via the inlet 104, and then enters the second chamber 17 via the nearly centrally defined through openings 122. The liquid flowing into the second chamber 17 thus strikes the center portion of the impeller 26 and is then evenly distributed to an outer edge of the impeller 26. The liquid is finally discharged out of the second chamber 17 via the outlet 110 by a centrifugal force caused by rotation of the impeller 26. Since the liquid does not directly strike the blades of the impeller 26 that are near the outer edge thereof, the flow turbulence is eliminated accordingly. The liquid circulating efficiency of the liquid cooling system is thus enhanced.

Referring to FIG. 4, a miniature pump according to an alternative embodiment of the present invention is shown. Most parts of the miniature pump of the alternative embodiment are the same as the preferred embodiment. Main differences are that in the alternative embodiment the first and second permanent magnets 260′, 340 are both cylindrical while in the preferred embodiment they are flat; a radial flux gap is thus formed between the first and second permanent magnets 260′, 340′. Another difference is that the spacing plate 12′ downwardly forms a protrusion 120′ for engaging with the top end of the shaft 20′, thereby limiting axial movement of the shaft 20′.

It is understood that the invention may be embodied in other forms without departing from the spirit thereof. The above-described examples and embodiments are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given above. 

1. A miniature pump for use with a liquid cooling system, comprising: a pump casing defining an enclosed space therein; a spacing plate arranged in the pump casing and dividing said enclosed space into a first chamber and a second chamber, the spacing plate defining a through opening at a center portion thereof to make the first and second chambers communicate with each other; an inlet formed on the pump casing communicating with the first chamber; an outlet formed on the pump casing communicating with the second chamber; and a liquid circulating unit received in said second chamber for circulating the liquid in the liquid cooling system.
 2. The miniature pump as described in claim 1, wherein the pump casing comprises a hollow main body transversely forming a partition wall therein and a top cover hermetically attached to a top end of the main body, and said enclosed space is formed between the partition wall and the top cover.
 3. The miniature pump as described in claim 2, wherein the liquid circulating unit comprises a shaft mounted between the partition wall and the spacing plate, and an impeller rotatably attached to the shaft.
 4. The miniature pump as described in claim 3, wherein the partition wall forms a shaft support defining a blind hole receiving an end of the shaft, and the spacing plate defines a positioning hole at a center thereof receiving an opposite end of the shaft therein.
 5. The miniature pump as described in claim 4, wherein the liquid circulating unit comprises a pair of locking rings attached to the shaft near the opposite ends thereof to limit axial movement of the shaft.
 6. The miniature pump as described in claim 3, wherein the partition wall forms a shaft support defining a blind hole receiving an end of the shaft, and the spacing plate forms a protrusion for engaging with an opposite end of the shaft to limit axial movement of the shaft.
 7. The miniature pump as described in claim 3, further comprising a motor driving unit located outside said enclosed space to drive the impeller to rotate.
 8. The miniature pump as described in claim 7, wherein the impeller carries a first permanent magnet, the motor driving unit comprises a motor having a rotor, and a second permanent magnet is attached to the rotor corresponding to the first permanent magnet.
 9. The miniature pump as described in claim 8, wherein the first permanent magnet is embedded in the impeller.
 10. The miniature pump as described in claim 8, wherein each of the first and second permanent magnets comprises a ring flat body, and an axial flux gap is created between the first and second permanent magnets.
 11. The miniature pump as described in claim 8, wherein each of the first and second permanent magnets comprises a cylindrical body, and a radial flux gap is created between the first and second permanent magnets.
 12. The miniature pump as described in claim 7, wherein the pump casing further comprises a bottom cover attached to a bottom end of the main body, and the motor driving unit is positioned between the partition plate and the bottom cover.
 13. A miniature pump for use with a liquid cooling system, comprising: a pump casing defining therein an enclosed space with an inlet and an outlet in communication with the enclosed space; a spacing plate arranged in the pump casing to divide the enclosed space into first and second chambers respectively communicating with the inlet and outlet; a liquid circulating unit received in the second chamber and comprising an impeller for circulating liquid in the liquid cooling system; and the spacing plate defining therein a through opening aligned with a center portion of the impeller for allowing the liquid in the first chamber to enter the second chamber.
 14. The miniature pump as described in claim 13, wherein the impeller comprises a plurality of blades extending from the center portion to an outer edge thereof.
 15. The miniature pump as described in claim 13, wherein the pump casing is generally cylindrical and the enclosed space is formed at one end of the pump casing.
 16. The miniature pump as described in claim 15, further comprising a motor driving unit received in an opposite end of the pump casing for driving the impeller of the liquid circulating unit to rotate.
 17. The miniature pump as described in claim 16, wherein the impeller carries a first permanent magnet, the motor driving unit comprises a rotor and a second permanent magnet attached to the rotor for rotating therewith, and the second permanent magnet corresponds to the first permanent magnet with a flux gap formed therebetween.
 18. The miniature pump as described in claim 16, wherein the pump casing comprises a hollow main body transversely forming a partition wall, a top cover hermetically attached to said one end of the main body to form the enclosed space between the top cover and the partition wall, and a bottom cover attached to said opposite end of the main body to form a receiving space between the partition wall and the bottom cover to receive the motor driving unit.
 19. A method for operating a liquid cooling system, comprising: providing a casing having an enclosed space for receiving cooling liquid of said liquid cooling system therein; providing an inlet and an outlet to said casing in communication with said enclosed space for said liquid to move into/out said casing; driving said liquid in said enclosed space to circulate through said inlet and outlet via an impeller; and guiding liquid flow moving into said casing from said inlet so as to have said liquid flow movable toward a predetermined portion of said impeller in order for lessening disturbance of said liquid flow on driving of said impeller.
 20. The method as described in claim 19, wherein a spacing plate is used to guide said liquid flow moving slowly toward a central portion of said impeller in said guiding step. 